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Objective To explore the feasibility of using the optimization parameters modification and optimization processes modification to reduce the total monitor units ( MUs ) in the Eclipse radiotherapy treatment planning system (TPS). Methods Based on the radiotherapy plan of 10 patients with nasopharyngeal carcinoma, a total of 90 plans were designed for 9 groups using different optimization parameters and processes. The total MUs and the exposure dose of the organs among the different plans were compared. Results There was no significant difference in the doses of the organs at risk (class I) under the premise of target dose requirements (all P>0.05). The increase of the weight of the target area and the organs at risk will increase the total MUs. The increase of the preset limit value of the minimum MUs in the subfield will reduce the total MUs. The increase of the fluence smoothness in the X and Y directions will increase the total MUs. An unreasonable minimum MU value will increase the total MUs. Under the condition that the organ exposure is not changed significantly, the influencing factors of MU are ranked as weight>fluence smoothness>minimum MUs. Conclusions Parameter setting and process planning can reduce the total MUs to a certain extent. However, due to the complexity of the influence of optimization parameters on the plan, the optimization process should be preferred. Especially in the Eclipse TPS, the method of gradual optimization to achieve the final dose distribution requirement and then remove the fluence re-optimization is more convenient and effective for reducing the total MUs.
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Objective To establish a mouse model of lymph node metastasis of breast cancer cells by luciferase imaging assay,to monitor early process of lymph node metastasis,and to evaluate the effect of X-ray radiation therapy on tumor.Methods The mouse mammary cancer cell line 4T1-Luc expressing luciferase was inoculated subcutaneously into the paw pad of nude mice to establish a model of subcutaneous lymph node metastasis.The lymph node metastasis in nude mice was continuously observed by in vivo fluorescence imaging system,and the nude mice with early lymph node metastasis of breast cancer cells were divided into control group and treatment group randomly.The radiotherapy effect was observed by in vivo fluorescence imaging system and evaluated by the pathological changes of HE staining of tumor tissue.Results A mouse lymph node metastasis model of breast cancer cells was successfully established,and the volume of primary tumor in paw correlated with the fluorescence photon number positively (r =0.958,P ＜ 0.001).On the twenty-fourth day after inoculation,the fluorescence photon number in pad tumor and popliteal fossa tumor of treatment group were significantly decreased in comparison with the control group (t =32.58,P ＜ 0.05),and the inhibition ratio of radiotherapy on tumor growth approached to 85 ％.HE staining showed that the apoptosis and necrosis in irradiated tumor was obviously higher than that in control group.Conclusions Bioluminescence imaging technique can be used to evaluate the effect of X-ray on breast cancer suppression and lymph node metastasis in mice.
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Objective To select an efficient ion exchange resin to purify the 60Co contaminated well-water for storing radioactive source and to ensure the radioactivity of 60Co in treated well-water below 10 Bq/L.Methods The radioactivity of 60Co in the water samples was measured by using the potassium cobaltinitrite coprecipitation-β counting method.The treatment efficiencies of two different ion exchange resins for the simulated 60Co-bearing waste water were compared to select a better one to dispose of the 60Co contaminated well-water.Results The treatment efficiency of MBD-15-SC mixed ion exchange resin was about 5.8 times higher than ZGCNR50 strong-acid cation exchange resin.The radioactivity of 60Co in the contaminated well-water could be reduced from 4.16 × 105 Bq/L to 1.16 Bq/L by two-stage sorption of MBD-15-SC mixed ion exchange resin.Conclusions Using several times of two-stage MBD-15-SC mixed ion exchange resin could effectively purify the 60Co contaminated well-water.The quality of the treated well-water could meet the sewage discharge standards.
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Objective To design a new pre-treatment device and to evaluate its efficiency in order to monitor the tritium levels in biological samples.Methods The detection efficiency of tritium was determined with standard tritiated water.Recovery of tritiated water and organically bound tritium (OBT) were detected with high, medium and low activities of standard tritiated water and 3H-TdR (tritiated thymidine), respectively.Comparison of three kinds of biological samples using different pre-treatment devices was shown.Results The standard curve can be used in environmental tritium measurement and the detection efficiency for tritium was 23.3%.When 40.0 g rice with standard HTO or 3H-TdR was pretreated with this device, the average recovery of HTO and OBT was about 95.4% , which showed good reproducibility.The comparison results were similar.Conclusions The pre-treatment device can be used to survey the OBT in environmental biological samples.
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Objective To compare the incorporation method of 3H-TdR and 125Ⅰ-UdR on determining the proliferation effect of lymphocytes. Methods The proliferation effects of lymphocyte and Daudi lymphoma cells were estimated by 3H-TdR and 125Ⅰ-UdR incorporation. Results The incorporating fraction of 3H-TdR and 125Ⅰ-UdR into lymphocyte was 20.95% ± 1.06% and 1.00% ±0.04%,respectively, and the incorporating fraction for the lymphoma cells was 29. 94% ± 4. 10% and 6. 02% ±0. 73% ,respectively. The incorporation fractions of 3H-TdR into lymphocyte and lymphoma cells were much higher than those of 125Ⅰ-UdR, but the incorporating fractions of 3H-TdR or 125Ⅰ-UdR into the lymphoma cells were much higher than those of lymphocytes. Conclusions For lymphocytes, 125Ⅰ-UdR cannot substitute 3H-TdR as a tracer agent. But for lymphoma cells, whether 125Ⅰ-UdR could be replace 3H-TdR or not needs further research.
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Objective To evaluate the killing effect and the uptake of 125I-UdR on human lymphoma Raji and Daudi cell lines. Methods The amount of 125I-UdR in the cells and cell nuclei were determined after incubation of different time in RPMI 1640 culturing medium containing different concentrations of 125I-UdR. The killing effects of 125I-UdR on Raji and Daudi cell lines were estimated through MTT assay and cell cycle was analyzed by propidium iodide (PI) staining. Results The amounts of 125I-UdR in Raji and Dandi cells and cell nuclei were much higher than that of Na125I(P < 0.05). The amounts of 125l-UdR in Raji and Daudi cells were 14414±95 and (6916± 53.69) Bq/106 cell when the concentration was 100 kBq/ml. The amounts of Na125I were 68± 3.8 and (324±32.8) Bq/106 cell. The uptake of 125I-UdR in Raji and Daudi cells and cell nuclei increased with the 125I-UdR concentration and incubated time. The cell surviving fractions of 125I-UdR groups was much lower than that of Na125I groups (P < 0.05). When the concentration was 500 kBq/ml and incubated time was 48 hours, the Raji and Dandi cell surviving fractions of125I-UdR groups were (19.78 ± 1.39)% and (43.17 ± 2.69) % ;those of Na125I groups were (79.10 ± 1.79) % and (80.36 ± 6.12) %. The surviving fractions of 125I-UdR groups reduced with the 125I-UdR concentration. Conclusions 125I-UdR can be specially ingested by Raji and Daudi cells and incorporated into DNA, then the cells will be killed. The uptake of 125I-UdR is dose and time dependent.
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Aim To investigate the specific binding of folate conjugated PGA to FR-positive tumor cells.Method Folate-PGA and PGA were radiolabeled with 125I by the Iodogen method to examine the binding of PGA to FR positive HeLa cells and SKOV3 cells, or FR negative A549 cells. Results 125I-folate-PGA showed specific bound to HeLa cells and SKOV3 cells; Scatchard analysis of the data estimated the Kd of binding to be 0.11 nmol?L-1 and 0.25 nmol?L-1 respectively. 125I-folate-PGA showed virtually little specific binding to A549 cells which lack folate receptors. Conclusions folate-PGA displayed high affinity and good targeting activities for FR-positive tumor cells and the data warranted further studies for enzyme prodrug therapy.